The invention relates to a fuel injection valve according to the definition of the species of claim 1 and claim 2.
Fuel injection valves are already known that can be operated electromagnetically and thus have a magnetic circuit comprising at least a magnet coil, a core an armature and a stationary pole. Such fuel injection valves are presented and described, for example, in such publications as German DE-OS 30 16 993, DE-PS 32 30 844, DE-PS 37 33 809, DE-PS 40 03 227 and DE-OS 195 03 821. Ferromagnetic (magnetically soft) materials are usually used for the solid core with a compact one-piece design (and for the movable armature). Ferritic chromium steel, a 13% chromium steel, for example, has proven to be an especially suitable material for cores in fuel injection valves. Such a ferritic chromium steel is a good compromise, because although it has somewhat less favorable magnetic properties in comparison with ferritic soft iron, for example, it is very suitable for use in a compact and highly structured fuel injection valve due to its good machinability and handling. If there is a change in magnetic flux density in the core carrying a magnetic flux due to the electric current flowing in the magnet coil, stresses are induced in the flux field perpendicular to the direction of flux, resulting in eddy currents. These eddy currents weaken the effective magnetic field, because they create an opposing field. The result is a magnetic circuit with a reduced efficacy which is to be improved according to this invention.